Toggle platen unit

ABSTRACT

A reciprocating platen unit for bidirectional printing having an arcuate work surface with supports extending radially downward therefrom, mounted in a frame by rollers on the bases of the supports reciprocating in horizontal guideways in the frame and cam follower rollers near the outer ends of the work surface interacting with symmetrical curvilinear cam plates forming upper portions of the sides of the frame. The length of travel of the support rollers and cam follower rollers is slightly more than required to rock the platen fully, thus permitting the platen to drop enough at each end of its excursion for work-piece manipulation. A rod secured between the supports and beneath the platen surface riding in a channeled member pivoted to the frame and an over-center spring provide stabilization of the platen.

ilnited States Patent 1191 Colwill 14 1 Apr. 16, 1974 TOGGLE PLATEN UNITI [75] Inventor: Richard II. Colwill, Victor, NY.

[73] Assignee: Burroughs Corporation, Detroit,

Mich.

221 Filed: Sept. 12,1972

21 Appl. No.: 288,426

[52] U.S. Cl. 101/297, 101/328 [51] Int. Cl. B41f 3/20, B41f 3/58 [58]Field of Search lOl/l25, 328, 297, 298, 101/327, 333, 371, 368

[56] References Cited UNITED STATES PATENTS 992,461 5/1911 'V'andercook1-01/297 x 857,721 6/1907 Clark 101 297 x 2,309,645 2 1943 Harrington etal. 101 297 x 1,655,792 1/192s Krell 101/297 x 2,227,877 1/19411,305,778 6 1919 Cushing et al. 101/269 FOREIGN PATENTS OR APPLICATIONS377,840

6/1923 Germany l0l/297 1,117,674 2/1956 France.... 101/297 PrimaryExaminerClyde I. Coughenout Attorney, Agent, or Firm-Leon E. Redman;Charles S. Hall; Edward G. Fiorito [5 7] ABSTRACT A reciprocating platenunit for bidirectional printing having an arcuate work surface withsupports extending radially downward therefrom, mounted in a frame byrollers on the bases of the supports reciprocating in horizontalguideways in the frame and cam follower rollers near the outer ends ofthe work surface interacting with symmetrical curvilinear cam platesforming upper portions of the sides of the frame. The length of travelof the support rollers and cam follower rollers is slightly more thanrequired to rock the platen fully, thus permitting the platen to dropenough at each end of its excursion for work-piece manipulation. A rodsecured between the supports and beneath the platen surface riding in achanneled member pivoted to the frame and an over-center spring providestabilization of the platen.

10 Claims, 4 Drawing Figures PATENTEBAPR 15 m4 $804315 sum 1 0F 2BACKGROUND OF THE INVENTION This invention relates generally to a platenassembly for a printing press and more specifically to an assembly witha platen having an arcuate work surface for printing in a line-by-linefashion with a true rolling motion in each direction of travel.

It is well-known in the prior art to employ a curved work surface platenin a printing press. However, prior to this invention, a platen assemblywould usually have to complete an entire two-stroke cycle, returning theplaten to its original position, before the curved work surface would beengaged in the printing operation again. Bulky, complex assemblies wereoften required to accomplish even this cycling of a curved work surfaceplaten which may include elongated t'racks positioned outside the rangeof travel of the platen. Often, sophisticated synchronization wasrequired for coordination of bed band platen operation.

Besides the lack of speed typically associated with a prior art curvedwork surface platen assembly, there was the tendency for the platen toslide, shift, or wobble during the printing operation due to thepressure between the platen and the bed. Any such sliding, shifting, orwobbling resulted in blurred printed matter, which was furtherexacerbated by the two-stroke action of the press.

SUMMARY OF THE INVENTION The principal object of this invention is toimprove reciprocating platen units having arcuate work surfaces forline-by-line printing.

Another object of the invention is to develop an improved reciprocatingplateunit for high precision printing on each excursion of the platen.

A further object of the invention is to improve the stabilization ofreciprocating platens having arcuate work surfaces.

BRIEF DESCRIPTION OF THE INVENTION In achieving the above-mentionedobjects an assembly is provided for reciprocating an arcuate platenwherein lower ends of radially extending supports at each side of theplaten are constrained to reciprocal horizontal motion while the motionof the operating end of the platen is restricted by a pair ofsymmetrical curvilinear-shaped cam plates. The linear horizontal motionof the lower end of the supports is permitted beyond what would benecessary for completion of a printing stroke in order to lower thelevelof the platen at each end of the excursion for insertion or removalof print media. A rod secured between the supports, riding in a pivotedchanneled member, and an over-center spring stabilize the platen.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing objects and advantagesof the invention, together with other objects and advantages, which maybe attained by its use, will be apparent from the following detaileddescription when read in conjunction with the drawing, wherein likenumerals identify corresponding elements:

FIG. 1 is an isometric perspective view of a toggle platen illustratingthe orientation of various elements of the present invention;

FIG. 2 is a cross section of the toggle platen taken along line 22 ofFIG. 4;

FIG. 3 shows the view of FIG. 1 partially broken away;

FIG. 4 is a front elevation view of the toggle platen of FIG. 1 with aflat bed disposed thereabove.

DESCRIPTION OF THE PREFERRED EMBODIMENT The toggle platen of theinvention is preferably incorporated in a flat bed printing press inwhich a stationary bed 12 (FIG. 4) is horizontal and above the platen.The platen assembly is preferably firmly mounted on a base 11 (FIG. 1)but, of course may be affixed directly to a floor or other foundation.

A frame 13 defined by parallel and opposite outer sidewalls 14 extendsupwardly from the base 11 for providing the principal support andrestraints for the arcuate work surface platen 23. The platen 23 isintegrally attached to supports 25 extending radially downwardly andinwardly from each end of the lower, or concave, surface of the platen.The supports 25 are attached at the center of the arc of the arcuatesurface of the platen 23. Mounted on the lower end of each of thesupports 25 is a roller 29 which is constrained to linear and preferablyhorizontal movement by a guideway 17 in the form ofa slot cut out ofeach of the sidewalls 14 of frame 13. A restraint abutment 19 may beinserted at each end of each slot 17 for protection of the rollers 29.The abutment 19 may be formed of such well-known materials as gumrubber, or a rubber plastic composition, for example.

The radius of curvature of the work surface 27 is substantially equal tothe perpendicular distance between the parallel paths of the axis of thehorizontally constrained support rollers 29 and the advancing print lineacross the bed 12 of the printer. Therefore, any desired radius ofcurvature of the work surface 27 may be employed if the bed 12 ispositioned the corresponding distance above the axis of the supportroller. Whenever the toggle platen 23 is engaged in printing, the lineof contact between the arcuate work surface 27 and the bed 12 will bedirectly above the support rollers 29.

With any given radius of curvature of the work surface 27, the operativesegment of the arc will usually be designed according to the maximumlength of printing on a page. For example, if the maximum length ofprinting on a page is l2 inches then the operative arc of the arcuatework surface 27 must be at least 12 inches and the. radius of curvaturewill dictate the length of the platen segment.

Cam follower rollers 33, 35 are rotatably mounted on the outer surfacesof supports 25 near each end of the platen segment and proximate theside edge of the curved work surface 27. Curvilinear cams 21, preferablysymmetrical about axis 22 (FIG. 1) are formed on the edges of thesidewalls 14 of the frame 13 and restrict the cam follower rollers 33,35 such that the curved work surface 27 rolls, without sliding, in astraight line motion in each direction.

The exact contour of the curvilinear cams 21 is purely a function ofwhere the cam follower rollers 33, 35 are positioned on the supports 25for any given radius of curvature of the work surface 27. The cam fol-25 equidistant from the center of the arc of the work surface 27 therebydefining the curvilinear cam surfaces 21 as symmetrical.

A brace rod 37 (FIGS. 2 & 4) joins the supports 25 under the lower orconcave surface of the platen 23 at the center of the are for addedplaten strength and integrity by keeping the supports 25 from spreadingoutwardly under the platen pressure as it cooperates with the bed 12.

Hooks 45 (FIGS. 3 & 4) are journaled on each end of the brace rod 37just inside each of the supports 25. The top ends of over-center springs43 are attached to hooks 45 while the bottom ends of the springs 43 aresecured to either the base plate 11, a foundation, or hooks 47 journaledto the bottom of frame 13 and extending upwardly therefrom adjacent thecenter of the horizontal guideways 17.

The major portion of the length of brace rod 37 is spanned by astabilizer channel member 39 having integral flanges 40 extendingdownwardly from each end. At a point opposite each axis of symmetry 22of the curvilinear cam plates 21 the flanges 40 are pivotally secured toan inner frame comprising support plates 15 disposed inside the supports25. The inner support plates 15 are firmly attached to the base 11 orother foundation.

Opposite parallel inner walls 42 of the stabilizer channel 39 (FIG. 2)maintain sliding contact with the brace rod 37 and provide the channelmember 39 with sufficient depth to continuously constrain the brace rod37 while it rides up and down therein as the platen 23 is reciprocated.With the brace rod 37 thus constrained to ride within the stabilizerchannel 39, the platen 23 is prevented from lateral twisting withrespect to the guideways l7 and the camming surfaces 21 or otherwisewobbling in the frame 13.

Any standard drive train may be connected to either or both of thesupports 25, or to the axles 30 of the rollers 29 for impartingreciprocating movement to the supports 25 and thereby to the platen 23.

The reciprocating platen 23 prints in a true line-byline fashion via thecurved work surface 27 as the rollers 29 are reciprocated between theabutments 19 of the linear guideways 17. The rollers 29 are driven alongthe guideways 17 during the first part of each excursion against thebias of the overcenter springs 43 (FIG. 3 & 4). After the platen 23 haspassed the center ofits excursion the springs 43 add their accumulatedenergy to the drive on the supports 25 to bring the platen quickly tothe end of the printing operation. The over-center springs 43 enable theplaten 23 to be toggled between stable states at each end of theexcursion of the platen. The springs 43 cooperate with the channelmember 39 to stabilize the platen for preventing undesired slide, shift,or wobble of the arcuate work surface during the true line-by-line highprecision bidirectional printing operation.

Whenever the support rollers 29 are at rest against abutments 19 ateither end of the guideways 17, the reciprocating platen 23 is in astable state. The platen is oscillated between these stable states byactuating whatever drive means is coupled to the toggle unit. Forinstance. when force is applied to a handle 41 coupled to a support 25(FIG. 1) the platen supports 25 are driven along the horizontalguideways 17. While the support rollers 29 are thus moving from one endto the other of the horizontal guideways 17, cam follower rollers 33, 35are moving in opposite directions along the 4 peripheries of thesymmetrical curvilinear cam portions 21 of the sidewalls 14 of frame 13.

For example, if the support rollers 29 are against the right abutments19, as seen in FIGS. 1 and 3, then the right cam follower rollers 35engage the top of the right side of symmetrical curvilinear cam portions21 of the sidewalls 14, while the left cam follower rollers 33 engagethe bottom ends of the left side of the curvilinear cam portions 21 ofthe sidewalls 14. As the support rollers 29 roll along the guideway 17toward the left abutments 19, the right cam follower rollers 35 movesdownward along the periphery of the right side of the cams 21. Being sorestricted, the arcuate work surface 27 of the platen 23 will rock fromright to left. This movement of the work surface 27 produces truelineby-line printing from right to left when employed in conjunctionwith a stationary flat bed 12 or with an identical toggle platen unit insyncronization and facing relationship substituting for a flat bed 12.

The length of the guideways 17 and the length of the cam portions 21being extended beyond that which is necessary for completion of aprinting stroke, permits the platen 23 to drop slightly at the end ofprinting resulting in a lowering of the entire arcuate work surface 27.By so lowering the platen 23 clearance is provided so that a printmedium (not shown) may be passed between the arcuate work surface 27 andthe stationary bed 12 without further movement of either the stationarybed 12 or the platen 23.

Another means for permitting print medium manipulation other than theabove-disclosed extension of curvilinear cam plates 21 and horizontalguideways 17 is by providing cut-out or shallow open areas portions 50(FIGS. 1 and 3) extending into both ends of the arcuate work surface 27extending into work surface otherwise available for printing. Of course,the cut-out portions 50 would have to be slightly wider than the widthof the print medium, and therefore span almost the entire width of thework surface and also slightly deeper than the thickness of the printmedium.

Another alternative for providing print medium clearance is to combinethe cut-out means and extension means such that the cut-out portion 50would extend into the printing area of the work surface 27 less than thethickness of the print medium, and the curvilinear cam plates 21 andhorizontal guideway 17 would not be extended as far as is necessary fordropping the entire platen 23 a distance equal to the print mediumthickness. Any combination of cut-out portion 50 depth and cam plate 21and horizontal guideway 17 extension providing sufficient clearance forprint medium manipulation could be employed.

After the print medium has been moved a predetermined length presentinga fresh print medium above the work surface 27 the above operation isreversed beginning with the support roller 29 being moved from its nowstable state against the left abutment 19. Now the arcuate surface 27rises slightly according to the extended contour of the cam 21 and thentravels back to the right with a true line-by-line high precisionprinting operation being completed on a fresh print medium on eachhalf-cycle of oscillation. Therefore, two distinctareas of printing aremade for each cycle of oscillation of the platen 23, and the printingrate has been significantly increased.

Although the prime embodiment of the invention was described in aprinting press environment, it is obvious that the invention would alsobe useful in almost any environment where an arcuate platen is employed.The curved work surface and the bed could be equipped with various tools(not shown) other than type elements. For example, punches could bemounted on the curved work surface 27 and dies mounted on the bed 12 forpunching feed holes along continuous form edges. Likewise a single punchand die (not shown) could be employed for punching envelope windows. Itis quite apparent that the invention would be similarly useful in otherenvironments such as pressing, perforating, cutting, transferring, orlaminating, wherein arcuate platens operate in combination or singlywith a flat surface.

What is claimed is:

1. In a platen assembly having an arcuate work surface and supportsextending radially outward from each side of the arcuate work surface ofthe platen, and a frame for mounting the platen, the improvementcomprising:

means for constraining the outward ends of said supports to linearmovement;

symmetrical curvilinear cam surfaces on said frame;

cam followers mounted on said platen continuously engaging saidcurvilinear cam surfaces; and said cam followers cooperating with saidconstraining means for restricting said arcuate work surface to rollingmotion.

2. In vthe assembly of claim 1 the improvement wherein said constrainingmeans comprises linear guideways in said frame and rollers mounted onthe outward ends of said supports for movement within said guideways.

3. In the assembly of claim 2 the improvement further comprising meansfor enabling said cam followers and said rollers to lower said platenfor accommodating workpiece insertion and removal. I

4. In a platen assembly having an arcuate work surface for line-by-lineprinting and including supports extending radially outward from eachside of the arcuate surface of the platen, and a frame for mounting saidplaten, the improvement comprising: means for constraining the outwardends of said supports to linear movement; 1

symmetrical curvilinear cam surfaces on said frame;

cam followers mounted on the sides of said platen continuously engagingsaid symmetrical curvilinear cam surfaces; and said cam followerscooperating with said constraining means for restricting said arcuatework surface to rolling motion for bidirectional line-by-line printing.

5. The assembly of claim 4 wherein said improvement further includesbracing means secured between said supports and channelled meansslidably enclosing said bracing means for maintaining the line of motionof said platen orthogonal to said lines of printing.

6. The assembly of claim 4 further including toggle means interactingwith said platen for adding accumulated energy to said platen during aportion of said printing and for maintaining said platen in a stablestate at the end of each printing excursion.

7. In the assembly of claim 4 the improvement wherein said constrainingmeans comprises linear guideways in said frame and rollers mounted onthe outward ends of said supports and positioned in said guideways.

8. In the assembly of claim 7 the improvement further comprisingresilient abutments at each end of said horizontal guideways forprotecti'ng'said rollers.

9. In the assembly'of claim 4 wherein said improvement further includesshallow open areas extending into and spanning almost the entire widthof each end of said work surface for print media manipulation.

10. In a platen assembly having an arcuate work surface and supportsextending radially outward from each side thereof, the improvementcomprising:

means for constraining the outward ends of said supports tosubstantially linear movement;

a frame including two opposite sidewalls for mounting the platen;

curvilinear carn'surfaces disposed on opposite edges of each of saidsidewalls, and

cam followers mounted on said platen, said supports being disposedadjacent and parallel to said opposite sidewalls and said cam followerson said platen continuously engaging said curvilinear cam surfacesbetween said cam followers and cooperating with said constraining meansfor restricting said arcuate work surface to rolling motion.

1. In a platen assembly having an arcuate work surface and supportsextending radially outward from each side of the arcuate work surface ofthe platen, and a frame for mounting the platen, the improvementcomprising: means for constraining the outward ends of said supports tolinear movement; symmetrical curvilinear cam surfaces on said frame; camfollowers mounted on said platen continuously engaging said curvilinearcam surfaces; and said cam followers cooperating with said constrainingmeans for restricting said arcuate worK surface to rolling motion.
 2. Inthe assembly of claim 1 the improvement wherein said constraining meanscomprises linear guideways in said frame and rollers mounted on theoutward ends of said supports for movement within said guideways.
 3. Inthe assembly of claim 2 the improvement further comprising means forenabling said cam followers and said rollers to lower said platen foraccommodating workpiece insertion and removal.
 4. In a platen assemblyhaving an arcuate work surface for line-by-line printing and includingsupports extending radially outward from each side of the arcuatesurface of the platen, and a frame for mounting said platen, theimprovement comprising: means for constraining the outward ends of saidsupports to linear movement; symmetrical curvilinear cam surfaces onsaid frame; cam followers mounted on the sides of said platencontinuously engaging said symmetrical curvilinear cam surfaces; andsaid cam followers cooperating with said constraining means forrestricting said arcuate work surface to rolling motion forbidirectional line-by-line printing.
 5. The assembly of claim 4 whereinsaid improvement further includes bracing means secured between saidsupports and channelled means slidably enclosing said bracing means formaintaining the line of motion of said platen orthogonal to said linesof printing.
 6. The assembly of claim 4 further including toggle meansinteracting with said platen for adding accumulated energy to saidplaten during a portion of said printing and for maintaining said platenin a stable state at the end of each printing excursion.
 7. In theassembly of claim 4 the improvement wherein said constraining meanscomprises linear guideways in said frame and rollers mounted on theoutward ends of said supports and positioned in said guideways.
 8. Inthe assembly of claim 7 the improvement further comprising resilientabutments at each end of said horizontal guideways for protecting saidrollers.
 9. In the assembly of claim 4 wherein said improvement furtherincludes shallow open areas extending into and spanning almost theentire width of each end of said work surface for print mediamanipulation.
 10. In a platen assembly having an arcuate work surfaceand supports extending radially outward from each side thereof, theimprovement comprising: means for constraining the outward ends of saidsupports to substantially linear movement; a frame including twoopposite sidewalls for mounting the platen; curvilinear cam surfacesdisposed on opposite edges of each of said sidewalls, and cam followersmounted on said platen, said supports being disposed adjacent andparallel to said opposite sidewalls and said cam followers on saidplaten continuously engaging said curvilinear cam surfaces between saidcam followers and cooperating with said constraining means forrestricting said arcuate work surface to rolling motion.